Biomedical subjects

C A Silagy

Publications and source records attributed to C A Silagy.

At least 37 records · Page 2Linked to original sources

PubMed1998

Systematic review of dietary intervention trials to lower blood total cholesterol in free-living subjects.

OBJECTIVES: To estimate the efficacy of dietary advice to lower blood total cholesterol concentration in free-living subjects and to investigate the efficacy of different dietary recommendations. DESIGN: Systematic overview of 19 randomised controlled trials including 28 comparisons. SUBJECTS: Free-living subjects. INTERVENTIONS: Individualised dietary advice to modify fat intake. MAIN OUTCOME MEASURE: Percentage difference in blood total cholesterol concentration between the intervention and control groups. RESULTS: The percentage reduction in blood total cholesterol attributable to dietary advice after at least six months of intervention was 5.3% (95% confidence interval 4.7% to 5.9%). Including both short and long duration studies, the effect was 8.5% at 3 months and 5.5% at 12 months. Diets equivalent to the step 2 diet of the American Heart Association were of similar efficacy to diets that aimed to lower total fat intake or to raise the polyunsaturated to saturated fatty acid ratio. These diets were moderately more effective than the step 1 diet of the American Heart Association (6.1% v 3.0% reduction in blood total cholesterol concentration; P<0.0001). On the basis of reported food intake, the targets for dietary change were seldom achieved. The observed reductions in blood total cholesterol concentrations in the individual trials were consistent with those predicted from dietary intake on the basis of the Keys equation. CONCLUSIONS: Individualised dietary advice for reducing cholesterol concentration is modestly effective in free-living subjects. More intensive diets achieve a greater reduction in serum cholesterol concentration. Failure to comply fully with dietary recommendations is the likely explanation for this limited efficacy.

Cholesterol↗

PubMed1997

Trials of providing costing information to general practitioners: a systematic review.

OBJECTIVE: To determine if providing general practitioners (GPs) with costing information can change their clinical behaviour and reduce medical costs. DATA SOURCES: MEDLINE, CINAHL, Health Plan and EMBASE and citations in review articles were searched for studies published between 1980 and 1996. STUDY SELECTION: Studies were included if they provided costing information to GPs with the aim of decreasing costs by changing behaviour, included an objective measure of GP performance or clinical care, and used a randomised or quasi-randomised controlled design, crossover design or a controlled time series. DATA EXTRACTION: Data extracted included study design, intervention used and measure of GP performance/clinical care (including test ordering, drug prescribing, hospital and primary care visits and costs). DATA SYNTHESIS: Six studies met the inclusion criteria. Computerised feedback on drug costs increased generic prescribing, and "academic detailing" decreased inappropriate prescribing of target drugs. Providing costing information also decreased ordering of diagnostic tests. "Gatekeeper" physicians reduced use of hospital and specialist services. Only two studies found the changes were sustained for nine months or longer and only one evaluated health outcomes. CONCLUSION: The provision of costing information can change GP behaviour in all service areas. Sustainability of these changes and linking of cost savings to health outcomes have not been well studied.

Family Practice↗

PubMed1997

The effectiveness of exercise training in lowering blood pressure: a meta-analysis of randomised controlled trials of 4 weeks or longer.

OBJECTIVE: To identify the features of an optimal exercise programme in terms of type of exercise, intensity and frequency that would maximise the training induced decrease in blood pressure (BP). DATA IDENTIFICATION: Trials were identified by a systematic search of Medline, Embase and Science Citation Index (SCI), previous review articles and the references of relevant trials, from 1980 until 1996, including only English language studies. STUDY SELECTION: The inclusion criteria were limited to randomised controlled trials of aerobic or resistance exercise training conducted over a minimum of 4 weeks where systolic and diastolic BP was measured. RESULTS: A total of 29 studies (1533 hypertensive and normotensive participants) were included, 26 used aerobic exercise training, two trials used resistance training and one study had both resistance and aerobic training groups. Aerobic exercise training reduced systolic BP by 4.7 mm Hg (95% CI: 4.4, 5.0) and diastolic BP by 3.1 mm Hg (95% CI: 3.0, 3.3) as compared to a non-exercising control group, however, significant heterogeneity was observed between trials in the analysis. The BP reduction seen with aerobic exercise training was independent of the intensity of exercise and the number of exercise sessions per week. The evidence for the effect of resistance exercise training was inconclusive. CONCLUSIONS: Aerobic exercise training had a small but clinically significant effect in reducing systolic and diastolic BP. Increasing exercise intensity above 70% VO2 max or increasing exercise frequency to more than three sessions per week did not have any additional impact on reducing BP.

Adolescent↗

PubMed1997

A meta-analysis of the effectiveness of acupuncture in smoking cessation.

The role of acupuncture in facilitating smoking cessation is controversial. A systematic review was undertaken, incorporating meta-analytic techniques, of all the available randomized controlled trials examining the effectiveness of acupuncture in smoking cessation. Based on the data from nine trials involving 2707 patients, the odds ratio of abstinence at 6-12 months' follow-up is 1.48 (95% confidence interval 1.13-1.94) with acupuncture compared to no acupuncture or sham acupuncture. The odds of quitting were higher in comparisons between acupuncture and no acupuncture (OR 2.41, CI: 1.52 to 3.83) than between acupuncture and sham acupuncture (OR 1.16, CI: 0.90 to 1.49). Many of the included trials were small and had methodological shortcomings. Therefore, while acupuncture appears promising, there is insufficient evidence at this point, without further research, to recommend it as an effective form of therapy.

Journal Article↗

PubMed1997

Exercise profile and subsequent mortality in an elderly Australian population.

Although the importance of exercise as a public health issue is increasingly recognised, little attention has been paid to exercise in very old people. We examined exercise patterns in 1788 subjects aged 70 years and over who were participating in the Australian Longitudinal Study of Ageing. In the two weeks before interview, 39 per cent of subjects had taken no exercise and only four per cent had exercised vigorously. When compared with those who took no exercise, exercisers were more likely to be male and younger, to self-report better health, to be former smokers and regular alcohol users. Mortality rates at two years follow-up were inversely related to the level of exercise at baseline. This research indicates that exercise is important for the very old as well as younger groups.

Aged↗

PubMed1995

A meta-analysis on the efficacy of epidural corticosteroids in the treatment of sciatica.

The efficacy of epidural corticosteroids in the treatment of sciatica was investigated by meta-analysis of all randomized controlled trials. Eleven suitable trials of good quality were identified involving a total of 907 patients. The use of epidural (caudal or lumbar) steroid in the short-term (up to 60 days) increased the odds ratio (OR) of pain relief ( > 75% improvement) to 2.61 (95% CI 1.90-3.77) when compared with placebo. Despite some variations in trial characteristics there was little evidence of significant heterogeneity (P = 0.07). When the trials were analysed for near or total relief of pain in the short-term the OR is 2.79 (95% CI 1.92-4.06), for heterogeneity (P = 0.07). For longterm relief of pain (up to 12 months) the OR is 1.87 (95% CI 1.31-2.68). Efficacy is independent of the route of injection; for caudal epidural steroid the OR is 3.80 (95% CI 1.36-10.6) and for the lumbar epidural steroid 2.43 (95% CI 1.77-3.74). Adverse events included dural tap (2.5%), transient headache (2.3%) and a transient increase in pain (1.9%). There were no reported longterm adverse events. In conclusion we present quantitative evidence from meta-analysis of pooled data from randomized trials that epidural administration of corticosteroids is effective in the management of lumbosacral radicular pain.

Adrenal Cortex Hormones↗

PubMed1994

The PACE pilot study: 12-month results and implications for future primary prevention trials in the elderly. (Prevention with low-dose Aspirin of Cardiovascular disease in the Elderly)

OBJECTIVE: To document compliance with medication, drop-out and drop-in rates, and baseline cardiovascular event rates during the pilot phase of the PACE (Prevention with low-dose Aspirin of Cardiovascular disease in the Elderly) study. DESIGN: Randomized, double-blind, placebo-controlled trial of low-dose aspirin therapy. SETTING: Community-based, in general practices and residential retirement villages, in Victoria, Australia. SUBJECTS: Four hundred persons aged 70 years and older (53% females), ambulatory and living independently, who volunteered to participate. None had significant vascular disease, peptic ulceration, hemorrhagic symptoms, or were currently taking non-steroidal anti-inflammatory drugs. MAIN OUTCOME MEASURES: Compliance with medication (assessed by pill count and platelet function tests), self-reported drop-out and drop-in rates, and incidence of cardiovascular events reported by participants and their general practitioners during a 12-month period. RESULTS: Two fatal cardiovascular events, three non-fatal coronary events, and eight non-fatal cerebrovascular events were observed during the 12-month period. These incidence figures were approximately 15%, 15%, and 40%, respectively, of those in the general population of the same age and sex, based on morbidity data available from the Australian Bureau of Statistics. Compliance to medication was excellent (87%), and premature withdrawal (other than for a study end point) was limited to 14.5%. Secondary 'softer' endpoints, such as transient ischaemic attack and unstable angina, necessitated patient withdrawal from randomized therapy and possibly contributed to the small number of primary 'hard' end points observed. The projected power of the main study to detect a 20% treatment effect on overall cardiovascular mortality in 15,000 subjects over a 4-year period may, therefore, be substantially reduced. CONCLUSIONS: These results suggest that any future primary prevention study of cardiovascular disease in the elderly examining the effect of low-dose aspirin on overall cardiovascular mortality will likely need to use much larger numbers of patients or use a combined end point of fatal and non-fatal ischemic events.

Aged↗

PubMed1994

A meta-analysis of the effect of garlic on blood pressure.

OBJECTIVE: To undertake a systematic review, including meta-analysis, of published and unpublished randomized controlled trials of garlic preparations to determine the effect of garlic on blood pressure relative to placebo and other antihypertensive agents. DATA IDENTIFICATION: Studies were identified by a search of Medline and the Alternative Medicine electronic databases, from references listed in primary and review articles, and through direct contact with garlic manufacturers. STUDY SELECTION: Only randomized controlled trials of garlic preparations that were at least 4 weeks in duration were deemed eligible for inclusion in the review. DATA EXTRACTION: Data were extracted from the published reports by the two authors independently, with disagreements resolved by discussion. RESULTS: Eight trials were identified (all using the same dried garlic powder preparation (Kwai) with data from 415 subjects included in the analyses. Only three of the trials were specifically conducted in hypertensive subjects, and many had other methodological shortcomings. Of the seven trials that compared the effect of garlic with that of placebo, three showed a significant reduction in systolic blood pressure (SBP) and four in diastolic blood pressure (DBP). The overall pooled mean difference in the absolute change (from baseline to final measurement) of SBP was greater in the subjects who were treated with garlic then in those treated with placebo. For DBP the corresponding reduction in the garlic-treated subjects was slightly smaller. CONCLUSIONS: The results suggest that this garlic powder preparation may be of some clinical use in subjects with mild hypertension. However, there is still insufficient evidence to recommend it as a routine clinical therapy for the treatment of hypertensive subjects. More-rigorously designed and analysed trials are needed.

Blood Pressure↗

PubMed1994

Review of 39 years of randomized controlled trials in the British Journal of General Practice.

BACKGROUND: Randomized controlled trials are being used increasingly to evaluate the effectiveness of health care interventions, including those in primary care. AIM: A study was undertaken to document the topic areas addressed by randomized controlled trials conducted in primary care and the methodological characteristics of these, based on a historical review of all trials published in the British Journal of General Practice (formerly the Research Newsletter and Journal of the Royal College of General Practitioners) between 1953 and 1991 inclusive. METHOD: Trials were identified by systematically hand searching all back issues. RESULTS: A total of 90 randomized controlled trials were identified, 78% of which were undertaken in general practice. The trials covered a wide range of topics; 62% examined pharmacological interventions, 21% non-pharmacological interventions, and 16% an intervention related to provision of an aspect of health service. Among the randomized controlled trials published there was a significant trend towards more reports on non-pharmacological trials in recent years (P < 0.001). The quality of trials, judged by the extent to which bias was controlled, varied considerably. Trials of pharmacological interventions generally controlled for selection bias at entry and at assessment of outcome more effectively than trials of non-pharmacological interventions. CONCLUSION: Some imaginative solutions to the logistic difficulties of conducting randomized trials in general practice were noted. These may serve as an incentive to those undertaking such studies in the future.

Community Health Services↗

PubMed1994

An analysis of randomized controlled trials published in the US family medicine literature, 1987-1991.

BACKGROUND: Randomized controlled trials (RCTs) are frequently used to evaluate the effectiveness of health care interventions in family medicine. The value of the information obtained from RCTs depends largely on the quality of design and the way in which they are conducted and reported. Despite the increasing number of RCTs being conducted in family medicine, there is a scarcity of descriptive data on the methodological characteristics, including design features and quality of RCTs in this setting. METHODS: All 55 RCTs published in four peer-reviewed US family medicine journals between 1987 and 1991 were identified and their methodological characteristics reviewed. Three potential sources of bias were assessed in each of the trial reports: (1) control of selection bias at entry, (2) control of selection bias after entry, and (3) control of bias in assessing outcome(s). RESULTS: Fifty-five RCTs published between January 1987 and December 1991 were identified in the four journals. The absolute number of RCTs published over the 5 years increased steadily, and there was a 49% increase in the proportion of RCT articles. Measures used to control for selection bias before entry into the study were reported in 14 (25%) of the RCTs, the statistical power of the trial in 5 (9%), and whether the study had been reviewed by an institutional review board in 6 (11%). CONCLUSIONS: The RCTs analyzed offered some imaginative solutions to the logistic difficulties of conducting RCTs in general practice. Nevertheless, the methodology and reporting of RCTs in the future should be improved.

Bias↗

PubMed1993

Adverse effects of low-dose aspirin in a healthy elderly population.

The adverse effects of low-dose aspirin (100 mg daily) in the elderly were studied over a 12-month period in a double-blind, randomized, placebo-controlled trial of 400 subjects who were 70 years of age or older and had no preexisting major vascular diseases at the time of entry. Subjects were randomized so that 200 subjects received low-dose enteric-coated aspirin (100 mg daily) and 200 subjects received placebo. Compliance with medication, assessed by pill count, was 86%. Gastrointestinal symptoms were reported by 18% (n = 36) of participants receiving aspirin and 13% (n = 26) of those receiving placebo. Clinically evident gastrointestinal bleeding occurred in 3% (n = 6) of subjects receiving aspirin and none receiving placebo. Aspirin-treated subjects had a significant decrease in mean hemoglobin levels of 0.33 gm/dl during the 12-month study period, which was significantly greater than the decrease in the placebo-treated group (0.11 gm/dl; p < 0.05). These rates of unwanted symptoms are comparable with previous studies that used higher doses of aspirin. Until the risk-benefit trade-off from the use of low-dose aspirin in the elderly is established with an appropriate clinical trial, caution should be exercised when this compound is used for primary prevention of cardiovascular disease in this age group.

Aged↗

PubMed1993

An analysis of review articles published in primary care journals.

Review articles play an important role in synthesizing primary research for dissemination to clinicians. In a previous study it was found that many review articles appearing in leading peer-reviewed general medical journals are not prepared systematically. Given that review articles feature prominently in primary care journals, this study assessed the extent to which review articles published in the seven main primary care journals during 1991 had been assembled using a systematic and scientific approach. A total of 28 review articles were identified covering a wide range of subject areas. However, when standard criteria were used to assess their methodological rigour, only 25% of the articles had a total score of more than 8 points (out of a possible 16). The validity of any conclusions or recommendations made in a poorly assembled review need to be carefully examined. Improving the methodological standards by which reviews are assembled in primary care journals should be seen as both a challenge and a priority.

Family Practice↗

PubMed1993

Comparison of repeated measurement of ambulatory and clinic blood pressure readings in isolated systolic hypertension.

Repeated clinic blood pressure measurement was compared with non-invasive ambulatory blood pressure monitoring in 10 elderly subjects with persistent isolated systolic hypertension and 11 normotensive controls. Mean clinic blood pressures +/- Standard Deviation (SD), at visit 1 were 165/81 +/- 12/7 mmHg and 136/87 +/- 14/10 mmHg respectively. Subjects were assessed on three subsequent occasions at weekly intervals. None were receiving antihypertensive or vasoactive medication. Clinical systolic and diastolic blood pressures were consistently higher than the corresponding mean daytime ambulatory blood pressures in both clinical groups at each of the visits. The difference was greater between the systolic pressures than between the diastolic pressures and these differences in systolic pressures were greater in the isolated systolic hypertensives (26 +/- 5 mmHg) than in the normotensives (7 +/- 18 mmHg). Daytime ambulatory readings aggregated from all four visits were normally distributed for both blood pressure components in both clinical groups. In the isolated systolic hypertension group the clinic systolic and diastolic blood pressure measurements corresponded to the 93rd and 85th percentiles of the ambulatory pressures respectively whereas in the normotensives the equivalent percentiles were 69 and 78. These results suggest a pressor response may largely account for the elevated systolic blood pressure seen in elderly subjects with sustained isolated systolic hypertension based on clinic readings.

Aged↗

PubMed1992

Crossover comparison of atenolol, enalapril, hydrochlorothiazide and isradipine for isolated systolic systemic hypertension.

The benefit of antihypertensive therapy in reducing cardiovascular morbidity and mortality associated with isolated systolic hypertension has now been established by the Systolic Hypertension in the Elderly Program. However, there is little information about the relative effectiveness of different drug regimens in this condition. This study compared the efficacy and tolerability of 50 mg of atenolol, 10 mg of enalapril, 25 mg of hydrochlorothiazide and 2.5 mg of isradipine in the treatment of isolated systolic hypertension. After a 3-week placebo run-in phase, 24 subjects were randomized into a 4-period double-blind crossover study by use of an orthogonal latin square design. Treatment periods were of 6 weeks' duration with titration to a higher dose after 4 weeks in those not reaching goal blood pressure (BP). Each active treatment was followed by a 3-week placebo washout. Casual clinic and 24-hour ambulatory BP (Accutracker II) were measured at the end of each treatment phase. Routine biochemistry was also performed after the placebo run-in, at the end of each active treatment phase, and after the placebo run-out. Of the 24 subjects entered (mean age 72.3 years, 38% men) 20 completed the whole study. Mean +/- standard deviation of supine clinic and daytime ambulatory BP on entry were 181/79 +/- 21/9 mm Hg and 165/82 +/- 23/15 mm Hg, respectively. All drugs reduced mean casual and ambulatory BP significantly relative to placebo but only hydrochlorothiazide and enalapril produced a consistent hypotensive effect throughout the entire 24-hour period. Isradipine and enalapril exhibited a relatively greater effect on reducing systolic BP than either hydrochlorothiazide or atenolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Haematological profile of healthy elderly Australians.

OBJECTIVE: To determine normal values for haematological parameters in healthy elderly persons, and document any changes in these over a 12 month period. DESIGN: The study was conducted as part of a randomised controlled trial of low-dose aspirin for primary prevention of cardiovascular disease in the elderly. All participants (380) had a full blood examination performed at entry, which was repeated after 12 months. The baseline results for all patients and the 12 month findings in a cohort of 162 persons allocated placebo were used in the present study. SETTING: Community-based (general practices and residential retirement villages). SUBJECTS: Persons aged 70 years and over (53% females) who were ambulatory, living independently, and volunteered to participate. None had significant vascular disease, peptic ulceration, haemorrhagic symptoms or were currently taking non-steroidal anti-inflammatory drugs. MAIN OUTCOME MEASURES: Full blood examination (excluding white cell differential counts) performed with a Technicon H1 analyser. RESULTS: The mean haemoglobin level +/- standard deviation (SD) was 14.69 +/- 1.10 g/dL (for men) and 13.72 +/- 1.05 g/dL (for women). Significant differences (P less than 0.001) in packed cell volume, red cell and platelet counts were observed between the two sexes. No clinically significant change was observed in any of the parameters over a 12 month period. CONCLUSIONS: Haematological reference values for healthy elderly Australians are consistent with normal values reported in younger populations for both sexes. As a result recommendations are provided for normal reference values among this group in an Australian setting.

Aged↗

PubMed1992

Current status of general practice research in Australia. Analysis of a national database.

OBJECTIVE: To describe the current status of general practice research activity in Australia. DESIGN: A descriptive survey of research projects included in a national research database, established by the Royal Australian College of General Practitioners. The study instrument was a mailed questionnaire. SETTING AND PARTICIPANTS: Research projects involving or directly related to general practice that had commenced in Australia since 1 January 1989. Responses were specifically sought from all universities, the Family Medicine Programme and the Royal Australian College of General Practitioners. RESULTS: Two hundred and thirty-seven projects from 130 different principal investigators, one-third of whom were not medical practitioners, were analysed. Over 85% of research took place in association with a recognised tertiary institution. Over half of the projects were descriptive only; the most common areas were medical education, prevention and screening and health services research. Of the 69 projects completed prior to 1991, 49 had been submitted for publication and 26 had been accepted. CONCLUSIONS: The amount of general practice research undertaken in Australia is still small in relation to the size of the workforce, and most are descriptive studies. This national database will enable longitudinal changes in such patterns to be effectively monitored.

Australia↗

PubMed1992

Epidemiologic aspects of isolated systolic hypertension and implications for future research.

Isolated systolic hypertension represents an important public health issue in the 1990s because of its prevalence in the elderly and its importance as a risk factor for cardiovascular morbidity and mortality. Methodologic differences may account for the wide variation between prevalence rates in studies reported. With the advent of newer methods of blood pressure (BP) assessment, such as noninvasive ambulatory BP monitoring, it may be possible to define more accurately the true population at risk. Recent data from the Systolic Hypertension in the Elderly Program has indicated a clear benefit of treatment with a reduction in total stroke of 36%, and a reduction of 25 and 32% in the combined end points of coronary heart disease and cardiovascular disease, respectively. Further studies are now required to elucidate what treatment regimens are most effective in preferentially reducing both systolic BP, without producing undesirable effects such as diastolic hypotension, and fatal and nonfatal events. One such trial is underway in Europe using a drug regimen different from that in the Systolic Hypertension in the Elderly Program. The cost implications associated with treating the population at risk are potentially large but these are now based on firm scientific evidence.

Aged↗

PubMed1992

Components of blood pressure variability in the elderly and effects on sample size calculations for clinical trials.

This study investigated components of blood pressure variability in the elderly using both ambulatory blood pressure monitoring (ABPM) and casual clinic blood pressure measurement. These were then used to determine sample size requirements for clinical trials of different design scenarios in the elderly. Twenty-six elderly subjects not receiving antihypertensive medication were recruited from general practices and seen on four occasions at weekly intervals. On each occasion of blood pressure was measured in the clinic using a standard mercury sphygmomanometer and then for 24 h using a noninvasive ambulatory monitoring device. The between subject and between subject/within occasion components of blood pressure variability were determined by analysis of variance and used to calculate to sample size requirements for parallel and crossover trials respectively. The between subject variance of mean blood pressure was 1/3 greater with clinic readings, except within a subgroup of subjects who had isolated systolic hypertension (ISH). Increasing the number of readings or occasions on which measurement was performed in a parallel group trial only reduced the variability substantially when the number of subjects involved was small. With crossover designs, the between subject component of variance is eliminated resulting in substantial reduction in sample size. Whereas 60 subjects with ISH would be required to detect a 10 mm Hg difference in systolic blood pressure between two treatments in a parallel design using casual readings, only 18 are required with a crossover trial. If ABPM is used the number of subjects required are 54 and 14, respectively. Reducing variability with ABPM involves a trade-off between the increased number of readings available with the technique against the highly uniform and standardized conditions used to determine clinic blood pressures. ABPM appears most useful as a strategy for reducing sample size in parallel group trials involving small numbers of subjects measured on one occasion.

Aged↗